Message345097
On 64-bit Python, many object sizes essentially doubled over 32-bit Python, because Python objects are so heavy with pointers. More recently, forcing alignment to 16 bytes on 64-bit boxes boosted the memory requirements more modestly.
But obmalloc's 256 KiB arenas and 4 KiB pools haven't changed since obmalloc was first written, and its `address_in_range()` machinery cannot deal with pools bigger than that (they're segfault factories, because the machinery relies on that a pool is no larger than a system page).
obmalloc's fastest paths are those that stay within a pool. Whenever a pool boundary is hit, it necessarily gets slower, then slower still if an arena boundary is hit.
So I propose to:
- Remove the 4 KiB pool limit, by making `address_in_range()` page-based rather than pool-based. Pools should be able to span any power-of-2 number of pages. Then a pool for a given size class will be able to hold that many more times as many objects too, and so stay in the fastest paths more often.
- On 64-bit boxes, increase both POOL_SIZE and ARENA_SIZE. |
|
Date |
User |
Action |
Args |
2019-06-10 00:36:19 | tim.peters | set | recipients:
+ tim.peters |
2019-06-10 00:36:19 | tim.peters | set | messageid: <1560126979.94.0.247484308186.issue37211@roundup.psfhosted.org> |
2019-06-10 00:36:19 | tim.peters | link | issue37211 messages |
2019-06-10 00:36:18 | tim.peters | create | |
|